The overall objective of this project is to investigate the causal association between human cytomegalovirus (human CMV) and various human malignancies, especially the virus and cell interactions that might bear upon the mechanism of herpesvirus oncogenesis. The long term objectives are directed by the following approaches: a) Detection of the existence of human CMV genome in various cancer tissues by nucleic acid hybridization techniques. b) Observation of virus and cell interaction by transforming various mammalian cells with viruses isolated from various tumor tissues and detection of virus genome and virus message in transformed cells. c) Genetic analysis of human CMV strains isolated from various clinical manifestations. d) Designation of the viral DNA restriction fragment which is responsible for the virus oncogenesis.